WO1995030800A1 - Hydraulic system for a mobile machine such as a wheel loader - Google Patents

Hydraulic system for a mobile machine such as a wheel loader Download PDF

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Publication number
WO1995030800A1
WO1995030800A1 PCT/EP1995/001556 EP9501556W WO9530800A1 WO 1995030800 A1 WO1995030800 A1 WO 1995030800A1 EP 9501556 W EP9501556 W EP 9501556W WO 9530800 A1 WO9530800 A1 WO 9530800A1
Authority
WO
WIPO (PCT)
Prior art keywords
valve
hydraulic
directional
pressure
tank
Prior art date
Application number
PCT/EP1995/001556
Other languages
German (de)
French (fr)
Inventor
Edwin Harnischfeger
Original Assignee
Mannesmann Rexroth Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mannesmann Rexroth Gmbh filed Critical Mannesmann Rexroth Gmbh
Priority to DE59504825T priority Critical patent/DE59504825D1/en
Priority to EP95917954A priority patent/EP0759109B1/en
Priority to JP7528635A priority patent/JPH09512869A/en
Priority to US08/737,363 priority patent/US5802847A/en
Publication of WO1995030800A1 publication Critical patent/WO1995030800A1/en
Priority to KR1019960706284A priority patent/KR970702951A/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2267—Valves or distributors
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • E02F9/2207—Arrangements for controlling the attitude of actuators, e.g. speed, floating function for reducing or compensating oscillations
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2271—Actuators and supports therefor and protection therefor

Definitions

  • the invention is based on a hydraulic system which is used for a mobile working device, in particular for a wheel loader, and which has the features from the preamble of claim 1.
  • the loader shovel In this switching position of the directional control valve, the loader shovel lies on the ground with its weight and can be pulled or pushed over it for leveling. It floats on the ground, so to speak, which is why the switching position of the directional valve in question is also referred to as the "swimming" switching position.
  • the "swimming" function as can be gathered from DE 41 29 509 AI, can also be implemented by an additional directional control valve the one that connects the two pressure chambers of each lift cylinder to one another and to the tank in a switch position.
  • a hydraulic system which has the features from the preamble of claim 1 and in which, according to the characterizing part of this claim, the shut-off valve is inserted into the directional control valve via which the two pressure chambers of the hydraulic cylinder are separated with " If pressure can be applied and / or can be connected together with the tank, it is integrated that the hydraulic accumulator and the first pressure chamber of the hydraulic cylinder can be connected to one another via the control slide of the directional control valve
  • One of the directional valves also fulfills the function of the shut-off valve, which means that the piping is less expensive, the construction is compact and space-saving, and the costs are reduced.
  • the second pressure chamber is simultaneously connected to the tank. This means that no negative pressure can develop in the second pressure chamber and the piston of the hydraulic cylinder can oscillate without cavitation.
  • a first directional valve via which the two pressure chambers of the hydraulic cylinder can be connected alternately to a hydraulic pump and to the tank, and a second directional control valve, via which the two pressure rooms together with can be connected to the tank, so that the "swimming" function can be implemented.
  • the shut-off valve is now advantageously integrated into the second directional valve, because then no fourth switching position is necessary for the first directional valve.
  • connection of the first pressure chamber of the hydraulic cylinder to the hydraulic accumulator can be established by actuating the second directional valve. If you disregard a possible pilot valve for the second directional valve, you do not have to: ⁇ : this directional valve, no further directional valve for the "damping" function of the hydraulic system must be operated.
  • valve housings of essentially the same design are used.
  • a first directional valve 10 and a second directional valve 11 can be seen, which form directly adjacent sections of a valve block 12, to which further directional valve sections, not shown, belong.
  • the directional control valve 10 serves to actuate two lift cylinders connected in parallel with one another and to raise and lower the loading shovel of a wheel loader via them.
  • Each lift cylinder 13 contains in a cylinder housing 14 a piston 15 having a piston rod 16, which divides the interior of the housing 14 into an annular pressure chamber 17 on the piston rod side and into a pressure chamber 18 away from the piston rod.
  • the piston rod-side pressure chambers 17 of the lift cylinder 13 are connected via a consumer line 19 to a first connection 20 of the directional control valve 10.
  • the housing 35 of the directional control valve 11 is largely identical to the housing 25 of the directional control valve 10. It has a channel 36 in the extension of the pressure channel 26 of the valve 10, a tank channel 38 in the extension of the tank channel 28 and a continuous circulation channel 41, which continues the circulation channel 31 of the directional control valve 10.
  • the circulation channel 41 is connected to the tank channel 38 in every position of the control slide 40 of the directional control valve 11, so that it is also possible to establish a permanent connection between the circulation channel 31 and the To produce tank channel 28 in the housing 25 of the directional control valve 10 and to dispense with a circulation channel in the housing 35 of the directional control valve 11.
  • the tank channels 28 and 38 are namely open to one another.
  • the channel 36 of the valve housing 35 to the pressure channel 26 of the valve housing 25 is shut off.
  • This shut-off can already be provided in the casting mold for the valve housing 35, but can also only be carried out subsequently.
  • the channel 36 is open to the side of the valve housing 35 facing away from the directional control valve 10. It is connected to a hydraulic accumulator 42.
  • the “swimming” function is thus realized by the corresponding actuation of the control slide 40.
  • the connection 20 of the directional valve 11 is connected to the channel 38, that is to say the tank 29, and the connection 21 to the channel 36, that is to say to the hydraulic accumulator 42.
  • the pressure spaces 17 of the lift cylinders 13 are thereby relieved of the load to the tank, while the pressure spaces 18 are connected to the hydraulic accumulator 42. Oil can therefore be pushed back and forth between the pressure chambers 18 and the hydraulic accumulator 42, so that the boom of the wheel loader with the loading shovel and the loader itself no longer form a rigid system and pitching vibrations are damped.
  • the "damping" function is thus realized by the further lateral position of the control slide 40.
  • the control slide 40 is shifted into this position either arbitrarily by the vehicle driver or automatically when the wheel loader has reached a certain driving speed.
  • An electromagnetically actuable pilot valve 50 is then actuated and a control pressure chamber 51 of the directional control valve 11, which is relieved to the tank in the rest position of the valve 50, is connected to a line 52 which is dependent on the maximum control pressure required for actuating the directional control valves of the block 12 is available, is acted upon.
  • the accumulator 42 can be charged up to an adjustable maximum pressure via an filling valve arrangement 60 and is connected to the pressure chambers 18 of the lift cylinders 13 via the filling valve arrangement 60.
  • this is done in that the valve arrangement 60 within the valve housing 35 of the directional valve 11 is connected to a channel leading to the connection 21 of this valve.
  • the connection could, however, also take place outside the valve housing 35 or inside the housing 25.
  • the valve arrangement 60 comprises a pressure reducing valve 61 and a check valve 62 which is connected between the pressure reducing valve and the hydraulic accumulator 42 and opens towards the hydraulic accumulator.
  • the hydraulic accumulator 42 is filled via the valves 61 and 62 up to the pressure prevailing in the pressure chambers 18, provided that this pressure does not exceed a value set on the pressure reducing valve ⁇ tet.
  • the pressure in the pressure chambers 18 usually remains below the set value, so that the maximum pressure that prevails in the hydraulic accumulator 42 is maintained in the hydraulic accumulator by the check valve 62.

Abstract

The invention starts from a hydraulic system for a mobile machine, in particular a wheel loader, the hydraulic system being equipped with the 'longitudinal oscillation damping' function. In accordance with a known hydraulic system of this type, the hydraulic system according to the invention has at least one hydraulic cylinder (13) with which a tool can be operated and whose inner space is divided by a piston (15) into two pressure chambers (17, 18); a stop valve (12) which connects one of the two pressure chambers (17, 18) to a hydraulic reservoir (42) which can be filled via a filling pipe; and a distributing valve (11) with a spool valve (40) for the separate pressurization of the two pressure chambers (17, 18) in the hydraulic cylinder (13) and/or for connecting them to a tank (29). To facilitate low-cost and space-saving construction of a system of this type, the stop valve is incorporated in the distributing valve (11) in such a way that the hydraulic reservoir (42) and the first pressure chamber (17) of the hydraulic cylinder (13) can be connected to each other via the spool valve (40) of the distributing valve (11).

Description

Hydraulische Anlage für ein mobiles Arbeitsgerät- insbesondere für einen RadladerHydraulic system for a mobile work tool - especially for a wheel loader
Die Erfindung geht aus von einer hydraulischen Anlage, die für ein mobiles Arbeitsgerät, insbesondere für einen Radlader ver- wendet wird und die die Merkmale aus dem Oberbegriff des An¬ spruchs 1 aufweist.The invention is based on a hydraulic system which is used for a mobile working device, in particular for a wheel loader, and which has the features from the preamble of claim 1.
Aus der DE 39 09 205 Cl ist es bekannt, die Nickschwingungen von Radladern, die insbesondere bei gefüllter Ladeschaufel und höhe¬ rer Fahrgeschwindigkeit auftreten, mit einem Dämpfungssystem zu dämpfen, das Bestandteil der hydraulischen Anlage des Radladers ist. Zur Schwingungsdämpfung sind die im allgemeinen zwei hydraulischen Liftzylinder zum Heben und Senken der Ladeschaufel über ein Absperrventil an einen Hydrospeicher anschließbar, der von einer Hydropumpe über eine Fülleitung aufgeladen werden kann. Das zwischen dem Hydrospeicher und den Liftzylindern ange¬ ordnete Absperrventil ist geschlossen, solange mit der Lade¬ schaufel gearbeitet wird, und kann vom Fahrer oder automatisch geöffnet werden, sobald beim Fahren Nickschwingungen auftreten oder sobald die Fahrgeschwindigkeit über einem bestimmten Wert von z.B. 6 km/h liegt. Zu einer hydraulischen Steueranordnung eines Radladers gehören, wie dies auch die DE 39 09 205 Cl zeigt, mehrere Wegeventile, von denen eines dazu dient, um zum Heben und Senken der Ladeschaufel die Liftzylinder mit Druckmit¬ tel zu versorgen. Nach der DE 39 09 205 Cl besitzt dieses Wege- ventil auch eine Schaltstellung, in der die beiden Druckräume jedes Liftzylinders mit dem Tank verbunden sind. In dieser Schaltstellung des Wegeventils liegt die Ladeschaufel mit ihrem Gewicht auf dem Boden auf und kann zur Planierung über diesen gezogen oder geschoben werden. Sie schwimmt gleichsam auf dem Boden, weshalb die betreffende Schaltstellung des Wegeventils auch als die Schaltstellung "Schwimmen" bezeichnet wird. Die Funktion "Schwimmen" kann, wie dies der DE 41 29 509 AI entnehm¬ bar ist, auch durch ein zusätzliches Wegeventil realisiert wer- den, das in einer Schaltstellung die beiden Druckräume jedes Liftzylinders miteinander und mit Tank verbindet.It is known from DE 39 09 205 Cl to dampen the pitching vibrations of wheel loaders, which occur in particular when the loading shovel is filled and the vehicle is traveling at a higher speed, with a damping system which is part of the hydraulic system of the wheel loader. To dampen vibrations, the generally two hydraulic lift cylinders for lifting and lowering the loading shovel can be connected via a shut-off valve to a hydraulic accumulator that can be charged by a hydraulic pump via a filling line. The shut-off valve arranged between the hydraulic accumulator and the lift cylinders is closed as long as the loading shovel is being used and can be opened by the driver or automatically as soon as pitching vibrations occur while driving or as soon as the driving speed exceeds a certain value of, for example, 6 km / h lies. A hydraulic control arrangement of a wheel loader includes, as is also shown in DE 39 09 205 Cl, a plurality of directional control valves, one of which serves to supply the lifting cylinders with pressure means for lifting and lowering the loading shovel. According to DE 39 09 205 Cl, this directional valve also has a switch position in which the two pressure chambers of each lift cylinder are connected to the tank. In this switching position of the directional control valve, the loader shovel lies on the ground with its weight and can be pulled or pushed over it for leveling. It floats on the ground, so to speak, which is why the switching position of the directional valve in question is also referred to as the "swimming" switching position. The "swimming" function, as can be gathered from DE 41 29 509 AI, can also be implemented by an additional directional control valve the one that connects the two pressure chambers of each lift cylinder to one another and to the tank in a switch position.
Der Erfindung liegt die Aufgabe zugrunde, eine hydraulische Steueranordnung mit den Merkmalen aus dem Oberbegriff des An- spruchs 1 so weiterzuentwickeln, daß eine kompakte und platzspa¬ rende Bauweise möglich ist, daß der Verrohrungsaufwand verrin¬ gert wird und daß die Herstellung kostengünstig sein kann.The invention has for its object to develop a hydraulic control arrangement with the features from the preamble of claim 1 so that a compact and space-saving design is possible, that the piping is reduced and that the production can be inexpensive.
Diese Aufgabe wird erfindungsgemäß durch eine hydraulische An¬ lage gelöst, die die Merkmale aus dem Oberbegriff des Anspruchs 1 aufweist und bei der gemäß dem kennzeichnenden Teil dieses An¬ spruchs das Absperrventil derart in das Wegeventil, über das die beiden Druckräume des Hydraulikzylinders getrennt mit "Druck be¬ aufschlagbar und/oder gemeinsam mit dem Tank verbindbar sind, integriert ist, daß der Hydrospeicher und der erste Druckraum des Hydrozylinders über den Steuerschieber des Wegeventils mit¬ einander verbindbar sind. Bei einer erfindungsgemäßen hydrauli¬ schen Anlage ist also neben den Wegeventilen nicht auch noch ein zusätzliches Absperrventil vorhanden. Vielmehr erfüllt eines der Wegeventile auch die Funktion des Absperrventils. Damit wird der Aufwand für die Verrohrung geringer, die Bauweise ist kompakt und platzsparend, und die Kosten sind reduziert.This object is achieved according to the invention by a hydraulic system which has the features from the preamble of claim 1 and in which, according to the characterizing part of this claim, the shut-off valve is inserted into the directional control valve via which the two pressure chambers of the hydraulic cylinder are separated with " If pressure can be applied and / or can be connected together with the tank, it is integrated that the hydraulic accumulator and the first pressure chamber of the hydraulic cylinder can be connected to one another via the control slide of the directional control valve One of the directional valves also fulfills the function of the shut-off valve, which means that the piping is less expensive, the construction is compact and space-saving, and the costs are reduced.
Vorteilhafte Ausgestaltungen einer erfindungsgemäßen hydrauli¬ schen Anlage kann man den Unteransprüchen entnehmen.Advantageous configurations of a hydraulic system according to the invention can be found in the subclaims.
So wird gemäß Anspruch 2 während einer Verbindung des ersten Druckraums mit dem Hydrospeicher gleichzeitig der zweite Druck¬ raum mit dem Tank verbunden. Somit kann im zweiten Druckraum kein Unterdruck entstehen und der Kolben des Hydrozylinders kann kavitationsfrei schwingen.Thus, according to claim 2, while the first pressure chamber is connected to the hydraulic accumulator, the second pressure chamber is simultaneously connected to the tank. This means that no negative pressure can develop in the second pressure chamber and the piston of the hydraulic cylinder can oscillate without cavitation.
Gemäß Anspruch 3 sind in Übereinstimmung mit der hydraulischen Anlage nach der DE 41 29 509 AI ein erstes Wegeventil, über das die beiden Druckräume des Hydrozylinders wechselweise mit einer Hydropumpe und mit dem Tank verbindbar sind, und ein zweites We¬ geventil vorhanden, über das die beiden Druckräume gemeinsam mit dem Tank verbindbar sind, durch das also die Funktion "Schwimmen" realisierbar ist. Vorteilhafterweise ist nun das Ab¬ sperrventil in das zweite Wegeventil integriert, weil dann keine vierte Schaltstellung für das erste Wegeventil notwendig ist.According to claim 3, in accordance with the hydraulic system according to DE 41 29 509 AI, a first directional valve, via which the two pressure chambers of the hydraulic cylinder can be connected alternately to a hydraulic pump and to the tank, and a second directional control valve, via which the two pressure rooms together with can be connected to the tank, so that the "swimming" function can be implemented. The shut-off valve is now advantageously integrated into the second directional valve, because then no fourth switching position is necessary for the first directional valve.
Gemäß Anspruch 4 kann nicht nur die Verbindung des ersten Druck¬ raums des Hydrozylinders mit dem Hydrospeicher, sondern auch die Verbindung des zweiten Druckr.~u.ms mit dem Tank durch eine Betä¬ tigung des zweiten Wegeventils hergestellt werden. Sieht man einmal von einem eventuellen Vorsteuerventil für das zweite We- geventil ab, so muß also auße:<: diesem Wegeventil kein weiteres Wegeventil für die Funktion "Dämpfen" der hydraulischen Anlage betätigt werden.According to claim 4, not only the connection of the first pressure chamber of the hydraulic cylinder to the hydraulic accumulator, but also the connection of the second pressure chamber to the tank can be established by actuating the second directional valve. If you disregard a possible pilot valve for the second directional valve, you do not have to: <: this directional valve, no further directional valve for the "damping" function of the hydraulic system must be operated.
Gemäß Anspruch 5 sind für das zweite Wegeventil und ein weiteres Wegeventil, die benachbarte Sektionen eines Ventilblocks bilden, im wesentlichen gleich ausgebildete Ventilgehäuse verwendet.According to claim 5 for the second directional control valve and a further directional control valve, which form adjacent sections of a valve block, valve housings of essentially the same design are used.
Ein Ausführungsbeispiel einer erfindungsgemäßen hydraulischen Anlage ist in der Zeichnung dargestellt. Anhand dieser Zeichnung wird die Erfindung nun näher erläutert.An embodiment of a hydraulic system according to the invention is shown in the drawing. The invention will now be explained in more detail with reference to this drawing.
In der Zeichnung erkennt man ein erstes Wegeventil 10 und ein zweites Wegeventil 11, die unmittelbar benachbarte Sektionen ei¬ nes Ventilblocks 12 bilden, zu dem noch weitere nicht näher dar¬ gestellte Wegeventilsektionen gehören. Das Wegeventil 10 dient dazu, um zwei parallel zueinander geschaltete Liftzylinder zu betätigen und über diese die Ladeschaufel eines Radladers zu he- ben und zu senken. Jeder Liftzylinder 13 enthält in einem Zylin¬ dergehäuse 14 einen eine Kolbenstange 16 aufweisenden Kolben 15, der das Innere des Gehäuses 14 in einen kolbenstangenseitigen, ringförmigen Druckraum 17 und in einen kolbenstangenabseitigen Druckraum 18 aufteilt. Die kolbenstangenseitigen Druckräume 17 der Liftzylinder 13 sind über eine Verbraucherleitung 19 mit ei¬ nem ersten Anschluß 20 des Wegeventils 10 verbunden. Die Druckräume 18 sind über eine Leitung 21 mit einem Anschluß 21 des Wegeventils 10 verbunden. Dieses Wegeventil 10 besitzt ein Ventilgehäuse 25, durch das in Richtung der Aneinanderreihung mit dem Wegeventil 11 ein Druck¬ kanal 26, der mit dem Druckanschluß einer Hydropumpe 27 verbun¬ den ist, und ein Tankkanal 28 hindurchgehen, der in einen Tank 29 mündet. Die Öffnungsquerschnitte dieser beiden Kanäle werden durch die Position des Steuerschiebers 30 des Wegeventils 10 nicht beeinflußt. Ein weiterer durch das Ventilgehäuse 25 hin¬ durchgehender Kanal 31 wird als Umlaufkanal bezeichnet, der in einer Mittelstellung des Steuerschiebers 30 offen ist und bei einer Verlagerung des Steuerschiebers 30 aus der federzentrier¬ ten Mittelstellung heraus in die eine oder in die andere Rich¬ tung bis zur völligen Absperrung immer mehr verschlossen wird. Der Umlaufkanal 31 führt auch durch die weiteren auf der der We¬ geventilsektion 11 abgelegenen Seite der Sektion 10 angeordneten Wegeventilsektionen des Ventilblocks 12 hindurch, ist durch die Steuerschieber der weiteren Wegeventilsektionen genauso wie durch den Steuerschieber 30 beeinflußbar und letztendlich mit dem Druckkanal 26 verbunden. Bei einer Verlagerung des Steuer¬ schiebers 30 aus der Mittelstellung heraus werden der Anschluß 21 mit dem Druckkanal 26 und der Anschluß 20 mit dem Tankkanal 28 verbunden. Dadurch werden die Druckräume 18 mit Druck beauf¬ schlagt und die Druckräume 17 zum Tank entlastet. Die Kolben¬ stangen 16 fahren aus, die Ladeschaufel des Radladers wird geho¬ ben. Bei einer Verlagerung des Steuerschiebers 30 in die entge- gengesetzte Richtung werden die Druckräume 17 mit Druck beauf¬ schlagt und die Druckräume 18 zum Tank entlastet. Die Ladeschau- feϊ senkt sich.In the drawing, a first directional valve 10 and a second directional valve 11 can be seen, which form directly adjacent sections of a valve block 12, to which further directional valve sections, not shown, belong. The directional control valve 10 serves to actuate two lift cylinders connected in parallel with one another and to raise and lower the loading shovel of a wheel loader via them. Each lift cylinder 13 contains in a cylinder housing 14 a piston 15 having a piston rod 16, which divides the interior of the housing 14 into an annular pressure chamber 17 on the piston rod side and into a pressure chamber 18 away from the piston rod. The piston rod-side pressure chambers 17 of the lift cylinder 13 are connected via a consumer line 19 to a first connection 20 of the directional control valve 10. The pressure chambers 18 are connected via a line 21 to a connection 21 of the directional valve 10. This directional control valve 10 has a valve housing 25, through which a pressure channel 26, which is connected to the pressure connection of a hydraulic pump 27, and a tank channel 28, which opens into a tank 29, pass through in the direction of the alignment with the directional control valve 11. The opening cross sections of these two channels are not influenced by the position of the control slide 30 of the directional valve 10. A further channel 31 passing through the valve housing 25 is referred to as a circulation channel, which is open in a central position of the control slide 30 and when the control slide 30 is displaced from the spring-centered central position in one or the other direction is closed more and more for complete isolation. The circulation channel 31 also leads through the other directional valve sections of the valve block 12 arranged on the side of the section 10 remote from the directional valve section 11, can be influenced by the control slide of the further directional valve sections as well as through the control slide 30 and is ultimately connected to the pressure channel 26. When the control slide 30 is moved out of the central position, the connection 21 is connected to the pressure channel 26 and the connection 20 to the tank channel 28. As a result, the pressure spaces 18 are pressurized and the pressure spaces 17 to the tank are relieved. The piston rods 16 extend, the loading shovel of the wheel loader is raised. When the control slide 30 is moved in the opposite direction, the pressure spaces 17 are pressurized and the pressure spaces 18 are relieved of pressure to the tank. The loading display lowers.
Das Gehäuse 35 des Wegeventils 11 ist weitgehend gleich dem Ge¬ häuse 25 des Wegeventils 10. Es besitzt einen Kanal 36 in Ver- längerung des Druckkanals 26 des Ventils 10, einen Tankkanal 38 in Verlängerung des Tankkanals 28 und einen durchgehenden Um¬ laufkanal 41, der den Umlaufkanal 31 des Wegeventils 10 fort¬ setzt. Der Umlaufkanal 41 ist, wie man aus dem Schaltsymbol er¬ sieht, in jeder Position des Steuerschiebers 40 des Wegeventils 11 mit dem Tankkanal 38 verbunden, so daß es auch möglich ist, eine dauernde Verbindung zwischen dem Umlaufkanal 31 und dem Tankkanal 28 im Gehäuse 25 des Wegeventils 10 herzustellen und auf einen Umlaufkanal im Gehäuse 35 des Wegeventils 11 zu ver¬ zichten. Die Tankkanäle 28 und 38 sind nämlich zueinander offen. Dagegen ist der Kanal 36 des Ventilgehäuses 35 zum Druckkanal 26 des Ventilgehäuses 25 hin abgesperrt. Diese Absperrung kann schon in der Gußform für das Ventilgehäuse 35 vorgesehen sein, jedoch auch erst nachträglich erfolgen. Zur dem Wegeventil 10 abgewandten Seite des Ventilgehäuses 35 hin ist der Kanal 36 of¬ fen. Er ist an einen Hydrospeicher 42 angeschlossen.The housing 35 of the directional control valve 11 is largely identical to the housing 25 of the directional control valve 10. It has a channel 36 in the extension of the pressure channel 26 of the valve 10, a tank channel 38 in the extension of the tank channel 28 and a continuous circulation channel 41, which continues the circulation channel 31 of the directional control valve 10. The circulation channel 41, as can be seen from the circuit symbol, is connected to the tank channel 38 in every position of the control slide 40 of the directional control valve 11, so that it is also possible to establish a permanent connection between the circulation channel 31 and the To produce tank channel 28 in the housing 25 of the directional control valve 10 and to dispense with a circulation channel in the housing 35 of the directional control valve 11. The tank channels 28 and 38 are namely open to one another. In contrast, the channel 36 of the valve housing 35 to the pressure channel 26 of the valve housing 25 is shut off. This shut-off can already be provided in the casting mold for the valve housing 35, but can also only be carried out subsequently. The channel 36 is open to the side of the valve housing 35 facing away from the directional control valve 10. It is connected to a hydraulic accumulator 42.
Wie das Wegeventil 10 besitzt auch das Wegeventil 11 zwei Ver¬ braucheranschlüsse 20 und 21, wobei der Verbraucheranschluß 20 wie der entsprechende Anschluß des Wegeventils 10 mit den Druck¬ räumen 17 und der Verbraucheranschluß 21 wie der entsprechende Anschluß des Wegeventils 10 mit den Druckräumen 18 der Liftzy- linder 13 verbunden ist. In der wiederum federzentrierten Mit¬ telstellung des Steuerschiebers 40 sind die beiden Verbraucher¬ anschlüsse 20 und 21 sowie die Kanäle 36 und 38 gegeneinander abgesperrt. In der einen seitlichen Stellung sind die Verbrau¬ cheranschlüsse 20 und 21 mit dem Kanal 38 und somit mit dem Tank 29 verbunden, während der Kanal 36 abgesperrt ist. Somit herrscht in beiden Druckräumen 17 und 18 der Liftzylinder 13 Tankdruck. Die Ladeschaufel eines Radladers kann zum Planieren des Bodens über diesen hinweggezogen werden. Durch die entspre¬ chende Betätigung des Steuerschiebers 40 wird also die Funktion "Schwimmen" realisiert. Bei einer Verlagerung des Steuerschie¬ bers 40 aus der Mittelstellung heraus in die entgegengesetzte Richtung wird der Anschluß 20 des Wegeventils 11 mit dem Kanal 38, also mit dem Tank 29, und der Anschluß 21 mit dem Kanal 36, also mit dem Hydrospeicher 42 verbunden. Die Druckräume 17 der Liftzylinder 13 sind dadurch zum Tank entlastet, während die Druckräume 18 mit dem Hydrospeicher 42 verbunden sind. Es kann also Öl zwischen den Druckräumen 18 und dem Hydrospeicher 42 hin und her geschoben werden, so daß der Ausleger des Radladers mit der Ladeschaufel und der Lader selbst kein starres System mehr bilden und Nickschwingungen gedämpft werden. Durch die weitere seitliche Stelllung des Steuerschiebers 40 ist also die Funktion "Dämpfen" realisiert.Like the directional control valve 10, the directional control valve 11 has two consumer connections 20 and 21, the consumer connection 20 like the corresponding connection of the directional control valve 10 with the pressure spaces 17 and the consumer connection 21 as the corresponding connection of the directional control valve 10 with the pressure spaces 18 of the Lift cylinder 13 is connected. In the again spring-centered central position of the control slide 40, the two consumer connections 20 and 21 and the channels 36 and 38 are shut off from one another. In one side position, the consumer connections 20 and 21 are connected to the channel 38 and thus to the tank 29, while the channel 36 is closed. Thus, the lift cylinder 13 tank pressure prevails in both pressure chambers 17 and 18. The loader bucket of a wheel loader can be pulled over the ground to level it. The “swimming” function is thus realized by the corresponding actuation of the control slide 40. When the control slide 40 is displaced from the central position in the opposite direction, the connection 20 of the directional valve 11 is connected to the channel 38, that is to say the tank 29, and the connection 21 to the channel 36, that is to say to the hydraulic accumulator 42. The pressure spaces 17 of the lift cylinders 13 are thereby relieved of the load to the tank, while the pressure spaces 18 are connected to the hydraulic accumulator 42. Oil can therefore be pushed back and forth between the pressure chambers 18 and the hydraulic accumulator 42, so that the boom of the wheel loader with the loading shovel and the loader itself no longer form a rigid system and pitching vibrations are damped. The "damping" function is thus realized by the further lateral position of the control slide 40.
Eine Verlagerung des Steuerschiebers 40 in diese Position er¬ folgt willkürlich vom Fahrzeugführer oder automatisch dann, wenn der Radlader eine bestimmte Fahrgeschwindigkeit erreicht hat. Es wird dann ein elektromagnetisch betätigbares Vorsteuerventil 50 betätigt und ein Steuerdruckraim 51 des Wegeventils 11, der in der Ruhestellung des Ventils 50 zum Tank entlastet ist, mit ei¬ ner Leitung 52 verbunden, die vom maximalen Steuerdruck, der für die Betätigung der Wegeventile des Blocks 12 zur Verfügung steht, beaufschlagt ist.The control slide 40 is shifted into this position either arbitrarily by the vehicle driver or automatically when the wheel loader has reached a certain driving speed. An electromagnetically actuable pilot valve 50 is then actuated and a control pressure chamber 51 of the directional control valve 11, which is relieved to the tank in the rest position of the valve 50, is connected to a line 52 which is dependent on the maximum control pressure required for actuating the directional control valves of the block 12 is available, is acted upon.
Der Speicher 42 ist über eine üllventilanordnung 60 bis zu ei¬ nem einstellbaren Höchstdruck aufladbar und dazu über die Füll¬ ventilanordnung 60 mit den Druckräumen 18 der Liftzylinder 13 verbunden. Im vorliegenden Beispiel geschieht dies dadurch, daß die Ventilanordnung 60 innerhalb des Ventilgehäuses 35 des Wege¬ ventils 11 mit einem zum Anschluß 21 dieses Ventils führenden Kanal verbunden ist. Die Anbindung könnte jedoch auch außerhalb des Ventilgehäuses 35 oder innerhalb des Gehäuses 25 erfolgen. Die Ventilanordnung 60 umfaßt ein Druckminderventil 61 und ein zwischen das Druckminderventil und den Hydrospeicher 42 geschal¬ tetes, zum Hydrospeicher hin öffnendes Rückschlagventil 62.The accumulator 42 can be charged up to an adjustable maximum pressure via an filling valve arrangement 60 and is connected to the pressure chambers 18 of the lift cylinders 13 via the filling valve arrangement 60. In the present example, this is done in that the valve arrangement 60 within the valve housing 35 of the directional valve 11 is connected to a channel leading to the connection 21 of this valve. The connection could, however, also take place outside the valve housing 35 or inside the housing 25. The valve arrangement 60 comprises a pressure reducing valve 61 and a check valve 62 which is connected between the pressure reducing valve and the hydraulic accumulator 42 and opens towards the hydraulic accumulator.
Wenn durch eine Betätigung des Wegeventils 10 die Druckräume 18 der Liftzylinder 13 mit Druck beaufschlagt werden, so wird der Hydrospeicher 42 über die Ventile 61 und 62 bis zu dem in den Druckräumen 18 herrschenden Druck gefüllt, sofern dieser Druck einen am Druckminderventil eingestellten Wert nicht überschrei¬ tet. Üblicherweise bleibt der Druck in den Druckräumen 18 unter¬ halb des eingestellten Wertes, so daß im Hydrospeicher 42 der aufgetretene Höchstdruck herrscht, der durch das Rückschlagven¬ til 62 im Hydrospeicher gehalten wird. If the pressure chambers 18 of the lift cylinders 13 are pressurized by actuating the directional control valve 10, the hydraulic accumulator 42 is filled via the valves 61 and 62 up to the pressure prevailing in the pressure chambers 18, provided that this pressure does not exceed a value set on the pressure reducing valve ¬ tet. The pressure in the pressure chambers 18 usually remains below the set value, so that the maximum pressure that prevails in the hydraulic accumulator 42 is maintained in the hydraulic accumulator by the check valve 62.

Claims

Patentansprüche Claims
1. Hydraulische Anlage für ein mobiles Arbeitsgerät, insbe¬ sondere für einen Radlader, mit einem über mindestens einen Hydraulikzylinder (13) betätigbaren Arbeitswerkzeug, insbeson- dere Ladeschaufel, mit einem das Innere des Hydraulikzylinders (13) in zwei Druckräume (17, 18) aufteilenden Kolben (15), mit einem Absperrventil, über das ein erster der beiden Druckräume (17, 18) mit einem über eine Fülleitung aufladbaren Hydrospei¬ cher (42) verbindbar ist, und mit einem Wegeventil (11) mit ei- nem Steuerschieber (40) zur getrennten Druckbeaufschlagung und/oder zur Verbindung der beiden Druckräume (17, 18) des Hydraulikzylinders (13) mit einem Tank (29), dadurch gekenn¬ zeichnet, daß das Absperrventil derart in das Wegeventil (11) integriert ist, daß der Hydrospeicher (42) und der erste Druck- räum (18) des Hydrozylinders (13) über den Steuerschieber (40) des Wegeventils (11) miteinander verbindbar sind.1. Hydraulic system for a mobile working device, in particular for a wheel loader, with a working tool that can be actuated via at least one hydraulic cylinder (13), in particular a loading shovel, with an inside of the hydraulic cylinder (13) in two pressure chambers (17, 18) dividing piston (15), with a shut-off valve, via which a first of the two pressure chambers (17, 18) can be connected to a hydraulic accumulator (42) that can be charged via a filling line, and with a directional valve (11) with a control spool ( 40) for separate pressurization and / or for connecting the two pressure chambers (17, 18) of the hydraulic cylinder (13) to a tank (29), characterized gekenn¬ characterized in that the shut-off valve is integrated in the directional control valve (11) that the The hydraulic accumulator (42) and the first pressure chamber (18) of the hydraulic cylinder (13) can be connected to one another via the control slide (40) of the directional control valve (11).
2. Hydraulische Anlage nach Anspruch 1, dadurch gekenn¬ zeichnet, daß während einer Verbindung des ersten Druckraums (18) mit dem Hydrospeicher (42) der zweite Druckraum (17) mit dem Tank (29) verbunden ist.2. Hydraulic system according to claim 1, characterized gekenn¬ characterized in that during a connection of the first pressure chamber (18) to the hydraulic accumulator (42), the second pressure chamber (17) is connected to the tank (29).
3. Hydraulische Anlage nach Anspruch 1 oder 2, dadurch ge¬ kennzeichnet, daß die beiden Druckräume (17, 18) des Hydrozylin¬ ders (13) über ein erstes Wegeventil (10) wechselweise mit einer Hydropumpe (27) und mit dem Tank (29) verbindbar sind, daß die beiden Druckräume (17, 18) über ein zweites Wegeventil (11) gemeinsam mit dem Tank verbindbar sind und daß das Absperrventil in das zweite Wegeventil (11) integriert ist.3. Hydraulic system according to claim 1 or 2, characterized ge indicates that the two pressure chambers (17, 18) of the Hydrozylin¬ ders (13) via a first directional valve (10) alternately with a hydraulic pump (27) and with the tank ( 29) that the two pressure chambers (17, 18) can be connected to the tank via a second directional valve (11) and that the shut-off valve is integrated in the second directional valve (11).
4. Hydraulische Anlage nach den Ansprüchen 2 und 3, dadurch gekennzeichnet, daß sowohl die Verbindung des ersten Druckraums (18) des Hydrozylinders (13) mit dem Hydrospeicher (42) als auch die Verbindung des zweiten Druckraums (17) mit dem Tank (29) durch eine Betätigung des zweiten Wegeventils (11) herstellbar ist. 4. Hydraulic system according to claims 2 and 3, characterized in that both the connection of the first pressure chamber (18) of the hydraulic cylinder (13) with the hydraulic accumulator (42) and the connection of the second pressure chamber (17) with the tank (29 ) can be produced by actuating the second directional valve (11).
5. Hydraulische Anlage nach Anspruch 3 oder 4, dadurch ge¬ kennzeichnet, daß das zweite Wegeventil (11) und ein weiteres Wegeventil (10) benachbarte Sektionen eines Ventilblocks (12) sind, daß das zweite Wegeventil (11) und das weitere Wegeventil (10) Ventilgehäuse (25, 35) besitzen, die im wesentlichen gleich ausgebildet sind und einen in Richtung der Aneinanderreihung verlaufenden, mit dem Kanal (36, 26) des anderen Ventilgehäuses (35, 25) fluchtenden Kanal (26, 36) aufweisen, von dem aus eine Verbindung zur den jeweiligen Steuerschieber (30, 40) aufnehmen- den Ventilbohrung besteht, daß die beiden Kanäle (26, 36) gegen¬ einander abgesperrt sind und daß der Kanal (36) des zweiten We¬ geventils (11) mit dem Hydrospeicher (42) und der Kanal (26) des weiteren Wegeventils (10) mit dem Druckanschluß der Hydropumpe (27) verbunden ist. 5. Hydraulic system according to claim 3 or 4, characterized ge indicates that the second directional valve (11) and a further directional valve (10) are adjacent sections of a valve block (12) that the second directional valve (11) and the further directional valve ( 10) have valve housings (25, 35) which are of substantially the same design and have a channel (26, 36) which runs in the direction of the row and is aligned with the channel (36, 26) of the other valve housing (35, 25) which consists of a connection to the respective control slide valve (30, 40), that the two channels (26, 36) are shut off from each other and that the channel (36) of the second directional control valve (11) with the Hydraulic accumulator (42) and the channel (26) of the further directional valve (10) is connected to the pressure connection of the hydraulic pump (27).
PCT/EP1995/001556 1994-05-07 1995-04-25 Hydraulic system for a mobile machine such as a wheel loader WO1995030800A1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
DE59504825T DE59504825D1 (en) 1994-05-07 1995-04-25 HYDRAULIC SYSTEM FOR A MOBILE WORKING DEVICE, IN PARTICULAR FOR A WHEEL LOADER
EP95917954A EP0759109B1 (en) 1994-05-07 1995-04-25 Hydraulic system for a mobile machine such as a wheel loader
JP7528635A JPH09512869A (en) 1994-05-07 1995-04-25 Hydraulic equipment for mobile implements, especially for wheel loaders
US08/737,363 US5802847A (en) 1994-05-07 1995-05-25 Hydraulic system for a mobile work device, in particular a wheel loader
KR1019960706284A KR970702951A (en) 1994-05-07 1996-11-07 Hydraulics for mobile machines, especially wheel loaders (HYDRAULIC SYSTEM FOR A MABILE MACHINE SUCH AS A WHEEL LOADER)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4416228.6 1994-05-07
DE4416228A DE4416228A1 (en) 1994-05-07 1994-05-07 Hydraulic system for a mobile working device, in particular for a wheel loader

Publications (1)

Publication Number Publication Date
WO1995030800A1 true WO1995030800A1 (en) 1995-11-16

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ID=6517607

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1995/001556 WO1995030800A1 (en) 1994-05-07 1995-04-25 Hydraulic system for a mobile machine such as a wheel loader

Country Status (6)

Country Link
US (1) US5802847A (en)
EP (1) EP0759109B1 (en)
JP (1) JPH09512869A (en)
KR (1) KR970702951A (en)
DE (2) DE4416228A1 (en)
WO (1) WO1995030800A1 (en)

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Also Published As

Publication number Publication date
US5802847A (en) 1998-09-08
EP0759109B1 (en) 1999-01-13
KR970702951A (en) 1997-06-10
DE59504825D1 (en) 1999-02-25
DE4416228A1 (en) 1995-11-09
EP0759109A1 (en) 1997-02-26
JPH09512869A (en) 1997-12-22

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